FIELD OF THE INVENTION
This invention relates to semiconductor devices and the testing thereof. While not so limited it is primarily concerned with integrated circuit memory devices and methods of testing the same. It is effective whether or not the memory array is embedded in logic.
For purposes of discussion the term "embedded" is defined as that condition of a memory array, circuit element, or even a circuit function on an LSI chip, when surrounded by other circuitry on the chip, such that the memory array, circuit element, or circuit function is not directly accessible, either in whole or in part, from the input and output terminals or pads of the chip.
A prime problem associated with the manufacture of memory arrays is the assurance that the device meets its performance specification. A prime problem in the use of memory arrays is the assurance that the control signals provided to the device fall within this same performance specification. As the performance of these devices is improved it becomes more and more difficult to insure that these problems are resolved in an economical manner.
As the level of integration increases, the circuit designer and component manufacturer are able to offer more and more complex memory arrays to the logic designer and system manufacturer, with higher and higher performance levels. This in turn requires more and more sophisticated circuitry external to the memory device to properly test and utilize it. Without an inexpensive means to guarantee ultimate performance the potential improvements in device design will be lost due to imprecision in the manufacturing test equipment and in the manufacturing tolerances of the supporting circuitry.